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Controlling air leakage through the building envelope remains a challenge, especially in light of the imperative to transition to a net-zero energy building sector and the increasing importance of indoor air quality during extreme weather events such as wildfires. The British Columbia Energy Step Code is a performance-based compliance option in the British Columbia Building Code which is intended to provide a transition pathway to net-zero energy ready construction by 2032. For small residential buildings, performance targets entail thresholds for the measured air leakage rate through the building envelope. This paper reports on the airtightness of the first 145 single- and two-family dwellings built under the Energy Step Code in Richmond, BC. Although the first phase of the implementation of the Energy Step Code in Richmond entailed no airtightness targets (only testing), results indicate improvement compared to the historical levels of airtightness in the region. [ABSTRACT FROM AUTHOR]

For decarbonization of the building sector to happen at scale, net-zero energy levels of operational efficiency must be achieved. A global consensus is emerging around the Passive House energy performance level (15 kWh/m2/a thermal energy demand) as "net-zero energy ready". Given the imperative to rapidly transform buildings and shortcomings of the traditional prescriptive approach, a growing number of building energy regulations are adopting the performance-based or outcome-based approach, seeking to mandate net-zero energy performance with ambitious timelines. Some such regulations are based on the Reference Building Approach (RBA) where the energy performance of a building is assessed based on a hypothetical building of the same design but meeting a set of minimum prescriptive requirements. More commonly, performance targets are defined in absolute terms, based on energy intensity metrics. Although the European version of the RBA reconciles the absolute and relative performance targets through mandatory statistical performance baselines, the RBA in North America is used as an independent alternative to absolute energy use/demand intensity metrics (kWh/m2/a). This paper examines the North American Reference Building Approach, focussing on its implementation in the British Columbia Energy Step Code as an instructive example. It is shown that the RBA has serious flaws. Most importantly, by creating a sliding scale, the RBA does not deliver net-zero energy performance, while incentivizing inefficient designs and poor energy modeling practices. Despite the regional focus of the data, the conclusions are applicable to the RBA in general. Based on the results, it is recommended that the use of the RBA in building energy codes and standards be discontinued. [ABSTRACT FROM AUTHOR]